Rantanen's linemates, center Nathan MacKinnon and forward Gabriel Landeskog, are equally impressed and certainly not surprised by his success after he had 84 points (29 goals, 55 assists) in 81 games last season.
"Last year he had a strong season from start to finish, constantly made plays and constantly found ways to create offense," said Landeskog, the Avalanche captain.
But until this season, his fourth in the NHL, Rantanen had been a well-kept secret. Last season he took a backseat to MacKinnon, who was a finalist for the Hart Trophy and scored 97 points (39 goals, 58 assists). In 2016-17, Rantanen had 38 points (20 goals, 18 assists) in 75 games but Colorado finished last in the NHL with a 22-56-4 record.
"When you have a player that scores 97 points, what [MacKinnon] had, that kind of stole the headlines," Landeskog said. "But I don't think Mikko minded that. He doesn't want attention necessarily. He doesn't care about that. He's trying to do what's best for the team.
"So it's good to see the League is finally catching on to what he can do. I've said it from Day One, that I don't think there's a ceiling on how good he can be. There's no limit to that. It's going to be fun to be his teammate."
All three of them are having fun this season. Rantanen, MacKinnon (24 points; 11 goals, 13 assists) and Landeskog (19 points; 11 goals, eight assists) have combined for 69 points, one more than the Bruins' top line of Brad Marchand, Patrice Bergeron and David Pastrnak.
Rantanen, who was selected No. 10 by the Avalanche in the 2015 NHL Draft and played nine games in 2015-16, said his progress last season was a product of many factors. The most important was his comfort level in the NHL.